Search: id:A080686
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%I A080686
%S A080686 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,22,23,24,25,
%T A080686 26,27,27,28,28,29,30,31,32,33,33,34,35,36,36,37,37,38,39,39,39,40,41,
%U A080686 42,43,44,44,45,46,47,48,48,48,49,49,49,50,51,52,53,53,54,54,55,55,56
%N A080686 Number of 19-smooth numbers <= n.
%C A080686 Range = primes 2 to 19. Input pn=19 in script below. Code below is much 
               faster than the code for cross-reference. For input of n=200 13 times 
               as fast and many times faster for larger input of n.
%o A080686 (PARI) smoothn(n,pn) = { for(m=1,n, pr=1; forprime(p=2,pn, pr*=p; ); 
               ct=1; for(x=1,m, f=0; forprime(y=nextprime(pn+1),floor(x), if(x%y 
               == 0,f=1; break) ); if(gcd(x,pr)<>1,if(f==0,ct+=1; )) ); print1(ct",
               "); ) }
%Y A080686 Cf. A071520, A051038.
%Y A080686 Sequence in context: A090322 A030066 A081331 this_sequence A036218 A025484 
               A030545
%Y A080686 Adjacent sequences: A080683 A080684 A080685 this_sequence A080687 A080688 
               A080689
%K A080686 easy,nonn
%O A080686 1,2
%A A080686 Cino Hilliard (hillcino368(AT)gmail.com), Mar 02 2003

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